Method and apparatus for cleaning a producing well

ABSTRACT

A method for cleaning the sand from an oil-bearing sand producing well penetrating a sandy stratigraphy and at least one apparatus for carrying out the method is disclosed. The apparatus comprises an injector at the top of a production tube for injecting water and a soap concentrate down the annulus externally of the tube in the well for forming a sand-bearing aqueous solution at the sand level and a pump in the tube at the sand level for forcing the sand-bearing foamy aqueous solution with the oil-bearing sand through the pump and up the production tube to the surface.

United States Patent 1191 Ping July 9, 1974 METHOD AND APPARATUS FOR 3,477,513 11/1969 Ferguson 166/304 CLEANING A PRODUCING WELL 3,685,807 8/1972 Campbell 166/312 X [75] Inventor: Willard H. Ping, Coalinga, Calif. Primary Examiner stephen J. Novosad 173 Assignee: Texaco Inc., New York, NY. Attorney, g n FirmT. y; Reis [22] Filed: Jan. 5, 1973 [57] ABSTRACT [21] PP N04 3211175 A method for cleaning the sand from an oil-bearing sand producing well penetrating a sandy stratigraphy 52 US. (:1 166/309, 166/312, 166/68 and at least one apparatus for carrying out the method [51] Int. Cl E2lb 43/00 is disclosed- The apparatus comprises an injector at 1581 Field of Search 166/311, 312, 304, 309, the top Of a Production tube for injecting Water and 11 166/68, 5 5 soap concentrate down the annulus externally of the tube in the well for forming a sand-bearing aqueous [56] References Cited solution at the sand level and a pump in the tube at UNITED STATES PATENTS the sand level for forcing the sand-bearing foamy 1 3 2 33 2 B "I 6/304 aqueous solution with the oil-bearing sand through the e 1s 2,704,979 3/1955 van Willigen 166/68 pump and up the producnon tube to the Surface 3,463,231 8/1969 Hutchison et al 166/312 X 5 Claims, 1 Drawing Figure 16 15 WATER I I I CHEMICAL INJECTION g" lNJECT1ON INLET '1' 19 INLET \V/ l Q /1 x x l 1 ;|Z\D'l' sa a d a v n A *1 A A 4 4 A6191 +L 4 1- 4 a q A A a A 4 11 f w l l w 4 l l l Q 3 1 1 TeooucTpumiE R/At; ;,1- 1. :I :1' I f, A l 4. 'q 7 1 A1 ra n i I. l1 l -IlTlT/I lIl|lTl\l l|ll lllll l-(ll l-lll METHOD AND APPARATUS FOR CLEANING A PRODUCING WELL BACKGROUND OF THE INVENTION Heretobefore during the production of oil from wells having a sandy subsurface stratigraphy, the production was allowed to continue until the well became completely choked up with sand. Then the well was cleaned out as illustrated in a typical manner in U. S. Pat. No. 3,662,828, and production resumed after possibly a long and costly delay for cleaning. While the above patented device uses a flushing tube-production tube an nulus for cleaning out the well after it has choked up until unproductive, the disclosed production tube-well wall annulus is utilized during production for cleaning out the well simultaneously with pumping of oil from the well for preventing the well from choking up and becoming unproductive.

The disclosed method of production eliminates the need for stopping production but instead cleans the well of sand or other foreign particulate matter during production, unless the method is started for the first time with a choked up well. Then the well would first need to be cleaned out sufficiently for production to start, and then the new method or apparatus used to finish cleaning the well during production until the well is clean and on full production.

OBJECTS OF THE INVENTION Accordingly, a primary object of this invention is to provide a method for cleaning a producing well in sandy stratigraphy.

Another primary object of this invention is to provide at least one apparatus for practicing or carrying out the method for maintaining a producing well clean when producing from a sandy subsurface stratigraphy.

Another object of this invention is to provide a mechanism for cleaning a producing well which is easy to operate, is of simple configuration, is economical to convert, and is of greater efficiency for cleaning of a producing well.

Other objects and various advantages of the disclosed method and apparatus for carrying out the method of cleaning and producing a well simultaneously will be apparent from the following detailed description, together with accompanying drawing, submitted for purposes of illustration only and not intended to define the scope of the invention, reference being had for that purpose to the subjoined claims.

BRIEF DESCRIPTION OF THE DRAWING The drawing diagrammatically illustrates by way of example, not by way of limitation, one form or mechanism for carrying out the method of the invention.

The FIGURE is a schematic view, with parts in section, of a typical wellbore using the invention for being cleaned of sand and producing oil simultaneously.

DESCRIPTION OF THE INVENTION ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Further, many modifications and variations of the invention as hereinbe fore set forth will occur to those skilled in the art. Therefore, all such modifications and variations which are within the spirit and scope of the invention herein are included. and only such limitations should be imposed as are indicated in the appended claims.

The following method prevents the accumulation of fill in the production tubing and casing and reduces the frequency of clean out work. In a production well with a tube down the center with the walls of the well forming an annulus therearound the tube, a pump is mounted in the bottom of the tube at the lowest producing level with all the production pumping mechanism equipped for sand production.

The method comprises:

a. Inject water down into the annulus at a rate equal to fluid flow from the production tube and check for sand in the produced fluid. If there is no sand, reduce the volume of water injected.

b. If sand is present in the produced fluid, mix a foamer, as any suitable liquid soap or detergent concentrate or a foamer such as but not limited to that disclosed in U. S. Pat. No. 3,463,231 of Aug. 26, 1969, with the injected water at the rate of approximately five gallons of foamer per barrels (42 gallon barrels) to form a foamy aqueous solution. An alternate foamer is TE-9, a liquid oxyalkylated phenol, manufactured by Tretolite, a division of Petrolite Corporation, a corporation of Missouri.

c. Force the foamer down the annulus to the bottom of the production tube as by pumping from the surface or by pumping from internally of the tube bottom, whereby a pressure drop results by the sand passing into the production tube with the oil. Foam is then generated. Each grain of sand is picked up by bubbles of foam and carried with the foamy fluid.

d. Pump the production oil and the foamy fluid with the sand through the pump and up the production tube to the surface at least at a rate faster than the sand can settle back to the bottom of the well bore.

e. Increase the water injection rate as the foamy fluid arrives at the surface until the sand flow into the wellbore stops and the well is making its normal production.

f. Cease supply of the foamer if the well is a low volume well while continuing the water injection for prevention of fall back of sand to the well bottom.

g. Continue the supply of the foamy mixture down the annulus, through the pump, and up the production tube to the surface until the well is making its normal production.

ONE MECHANISM FOR PRACTICING THE METHOD Added to the above described producing well is a conventional water injector positioned at the top of the well and supplied with water from pipe 16 for ejecting the water down an annulus 17 formed between production tube 11 and the walls of wellbore casing 14 and 14a. The lower end of the production tube 11 with pump 12 therein is positioned just above the loose sand 18. If the pump and well are sanded up, the sand has to first be cleaned out by any conventional method down to where the well is at least partially on production, as the sand level indicated in the drawing, prior to operation of the mechanism for performing the new method. Pump 12 and attendant downhole equipment must be equipped for sand production.

Pipe 19 supplies the liquid soap described above to the ejector 15 for being mixed with the water for forming an aqueous solution and circulated down the annulus with the water, through the pump 12., and up the production tube 11 with the sand.

in operation, the mechanism performs the method as described above. Prior to the well being placed on pro duction, the maximum capacity of the pump for the existing conditions is calculated. Then during production of the well, when injection of water is begun, the rate of water injection is made slightly higher than the pump capacity.

Briefly, injector l5 injects or forces water and liquid soap or the like from the supply pipes 16 and 19, respectively, down the annulus 17, forms a foamy aqueous solution at the pump 12, picks up all sand in the vicinity, and carries the sand from the pump up the pro duction tube 11 with the production fluid to the surface to be separated there by conventional methods and apparatuses.

Water injection may continue at a rate to maintain a balance between reservoir potential and pump capacity.

The fluid velocity in the production tubing may be increased by reducing the tubing size in the well.

Accordingly, it will be seen that the disclosed method, and apparatus for carrying out or practicing the method for cleaning a producing well without requiring stopping of production of the well meets each of the objects set forth hereinbefore.

While only one method of the invention and one mechanism for carrying out or practicing the method has been disclosed, it will be evident that various other methods and modifications are possible in the arrangement and construction of the disclosed method and apparatus for maintaining a producing well in a sandy subsurface stratigraphy clean of sand without departing from the scope of the invention and it is accordingly desired to comprehend within the purview of this invention such modifications as may be considered to fall within the scope of the appended claims.

I claim:

1. A method for cleaning foreign particulate matter from the bottom of a producing well having a production tube internally thereof forming an annulus with the well wall and having a pump for pumping producing fluid from the production tube comprising the steps of,

a. injecting water down into the annulus at a rate slightly greater than the pump capacity,

b. mixing a foamer with the injected water at the rate of five gallons of foamer per barrels of water for forming a foamy water for picking up the foreign particulate matter,

0. pumping the production fluid and the foamy water with the foreign particulate matter from the bottom of the well up through the production tube to the surface,-

d. balancing the water injected with the fluid produced, and

e. with the absence of foreign material reduce the volume of water and foamer injected down the annulus.

2. An apparatus for cleaning an oil well which is producing oil-bearing sand from a sandy stratigraphy comprising,

a. a production tube positioned centrally of the producing well down to the sandy stratigraphy forming an annulus between the production tube and the walls of the producing well,

b. a fluid pump mounted in the production tube adja cent the sandy stratigraphy for pumping the oilbearing sand up the production tube,

c. an injector mounted on the production tube at the top of said annulus, said injector comprising a water injection inlet and a chemical foaming agent injection inlet opening into said annulus for injecting water and a foamer down said annulus to the sandy stratigraphy for forming a sand-bearing foamy aqueous solution, and

d. pump means for pumping the oil-bearing sand and the sand-bearing foamy aqueous solution through the pump and up the production tube to the sur-- face.

3. An apparatus as recited in claim 2 wherein,

a. the oil-bearing sand produced from the well also includes sand-bearing oil.

4. An apparatus for cleaning an oil well which is producing sand-bearing oil from a sandy stratigraphy comprising,

a. production tube means for being positioned centrally in the well for forming an annulus between said production tube means and walls of the well,

b. pump means in the production tube means at the location of the sandy stratigraphy for pumping the sand-bearing oil up the production tube means,

0. injector means at the top of said annulus, said injector means comprising a water injection inlet means and a foamer inlet means opening into said annulus for injecting water and a foamer down said annulus to the sandy stratigraphy for forming a sand-bearing foamy aqueous solution, and

d. said pump means in said production tube means pumps said sand-bearing foamy aqueous solution with sand-bearing oil through said pump means and up said production tube means to the surface.

5. An apparatus as recited in claim 4 wherein,

a. said sand-bearing oil prbduced from the well also includes oil-bearing sand. 

1. A method for cleaning foreign particulate matter from the bottom of a producing well having a production tube internally thereof forming an annulus with the well wall and having a pump for pumping producing fluid from the production tube comprising the steps of, a. injecting water down into the annulus at a rate slightly greater than the pump capacity, b. mixing a foamer with the injected water at the rate of five gallons of foamer per 100 barrels of water for forming a foamy water for picking up the foreign particulate matter, c. pumping the production fluid and the foamy water with the foreign particulate matter from the bottom of the well up through the production tube to the surface, d. balancing the water injected with the fluid produced, and e. with the absence of foreign material reduce the volume of water and foamer injected down the annulus.
 2. An apparatus for cleaning an oil well which is producing oil-bearing sand from a sandy stratigraphy comprising, a. a production tube positioned centrally of the producing well down to the sandy stratigraphy forming an annulus between the production tube and the walls of the producing well, b. a fluid pump mounted in the production tube adjacent the sandy stratigraphy for pumping the oil-bearing sand up the production tube, c. an injector mounted on the production tube at the top of said annulus, said injector comprising a water injection inlet and a chemical foaming agent injection inlet opening into said annulus for injecting water and a foamer down said annulus to the sandy stratigraphy for forming a sand-bearing foamy aqueous solution, and d. pump means for pumping the oil-bearing sand and the sand-bearing foamy aqueous solution through the pump and up the production tube to the surface.
 3. An apparatus as recitEd in claim 2 wherein, a. the oil-bearing sand produced from the well also includes sand-bearing oil.
 4. An apparatus for cleaning an oil well which is producing sand-bearing oil from a sandy stratigraphy comprising, a. production tube means for being positioned centrally in the well for forming an annulus between said production tube means and walls of the well, b. pump means in the production tube means at the location of the sandy stratigraphy for pumping the sand-bearing oil up the production tube means, c. injector means at the top of said annulus, said injector means comprising a water injection inlet means and a foamer inlet means opening into said annulus for injecting water and a foamer down said annulus to the sandy stratigraphy for forming a sand-bearing foamy aqueous solution, and d. said pump means in said production tube means pumps said sand-bearing foamy aqueous solution with sand-bearing oil through said pump means and up said production tube means to the surface.
 5. An apparatus as recited in claim 4 wherein, a. said sand-bearing oil produced from the well also includes oil-bearing sand. 